Peel sweet potatoes and slice thinly with a food processor.Lay potato slices out in pie dish in a crust-like fashion, spray with oil, and bake on 400 degrees fahrenheit for 15 minutes. (After crust has baked, reduce oven to 375 degrees fahrenheit.)Spray a saute pan with oil and saute sliced onion and crushed garlic clove until lightly browned, about 7 minutes. Stir in spinach and saute until wilted and tender, about 4 minutes. Drain spinach over the sink to rid excess liquid.Blend eggs and mozzarella in a medium bowl. Add herbs, white cheddar cheese, and miso {or tahini or nothing}.Add spinach/garlic/onion mix to the egg/cheese mixture. Add salt and pepper to taste. Place the combined mixtures in the potato crust. Sprinkle with parmesan cheese on top.In a 375 degree oven, bake until the quiche is firm and the cheese has browned, about 40 minutes.Tastes best a little warm.